9905-871

About the 9905-871

With the 9905-871, operators can be sure of their protection against overspeed conditions. The two-out-of-three vote configuration of this system will still provide an accurate output even if one of the three, identical speed-sensing units is offline. These hardware votes are achieved as each unit performs its own speed calculations while monitoring prime mover speed through its own magnetic pickup (MPU). A trip relay is activated when an overspeed condition is detected.

When an overspeed condition occurs, if the current speed is greater than the previous peak speed, the new peak speed is updated and stored in non-volatile memory. Both the peak speed as well as the current speed of any single speed-sensing unit can be viewed on the unit’s operator interface LCD.

Along with an LCD, the operator interface of each unit in the 9905-871 has a touchpad and several LEDs. These LEDs indicate the functional status of hardware and systems within the corresponding unit. Details on 9905-871 operations and troubleshooting can be found in Woodward’s ProTech 203 Overspeed Protection System Manual 85191 (version B).

9905-871 is a de-energize-to-trip model. All three of the speed-sensing units have their own 220 Vac power supplies, and a voltage range of 180–264 Vac, 7.25 W. Additional specs and product info on model 9905-871 can also be found in Manual 85191 (B).